Abstract 15566: Autonomic Modulation by Cardiopulmonary Rehabilitation in Heart Failure With Reduced Ejection Fraction: Who Benefits?
Bibliographic record
Abstract
Introduction: Elevated muscle sympathetic nerve activity (MSNA) both at rest and during dynamic cycling relates inversely to peak oxygen uptake (VO 2peak ) in patients with heart failure due to a reduced ejection fraction (HFrEF). We observed a drop in MSNA both rest (-6±2 bursts/min) and mild exercise (-4±2) in HFrEF patients after 6 months of cardiac rehabilitation. Hypothesis: We hypothesized that after training those HFrEF patients with LOW VO2peak (less than median 74% of age predicted) would have a larger decrease in MSNA during dynamic exercise than those with HIGH VO2peak (over 74%). Methods: In 21 optimally treated HFrEF patients (5 Female) (13 HIGH: mean VO 2peak =26 ml·kg/min; 98% of predicted; 8 LOW VO 2peak =12; 50%) we assessed VO 2peak (open-circuit spirometry), heart rate variability (HRV) and fibular MSNA (microneurography) at rest, during 1-leg cycling (2 min each of mild and moderate intensity upright 1-leg cycling, n=19) and recovery before and after 6 months of exercise training (45 min aerobic exercise, 5 days/ wk at 60-70 % of VO 2peak; and resistance training 2 days/wk). Results: HIGH and LOW groups had similar age (63±3 vs 63±4 years) , LVEF (30±2 vs 28±3%), BMI, resting heart rate (HR), blood pressure and MSNA (52±3 vs 50±3 bursts/min). Training increased VO 2peak in both groups (main effect P=0.009), with no group difference in HR response or ratings of perceived exertion. MSNA at rest tended to decrease after training in the HIGH but not LOW group (interaction P=0.08). MSNA during cycling increased in both HIGH (P=0.04) and LOW (P<0.001) groups but was blunted post-training in the HIGH group only (P=0.04 vs. 0.90 in LOW). Training-induced sympatho-inhibition during exercise recovery occurred in the HIGH but not LOW group (interaction P=0.01). In contrast, HRV was not improved by training in either group. Conclusions: Contrary to our hypothesis, the sympatho-inhibitory effect of 6 months of exercise-based cardiac rehabilitation favours HFrEF patients with an already normal VO 2peak . This suggests that increasing initially low VO 2peak may be insufficient to trigger beneficial exercise and recovery autonomic modulation and altered training paradigms may be required in such patients. Funded by Canadian Institutes for Health Research (CIHR)
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".